Self-Locking Screwing Attachment Device And Assembly Provided With Same

ABSTRACT

The invention relates to a self-locking screwing attachment device ( 1   a,    1   b ) including a nut ( 2   a,    2   b ) screwed onto a threaded tip ( 3   a,    3   h ) extending in a screwing axis (X), characterised in that the nut ( 2   a,    2   b ) includes: a first element ( 6   a,    6   b ) rotating relative to the tip ( 3   a,    3   b ) when screwing; a second element ( 13   a,    13   b ) rotatably engaged with the tip ( 3   b ) or an adjacent part ( 5 ) to be assembled, the tip ( 3   a ) passing therethrough; a stop member ( 23   a,    23   b ) rotatably secured to the first element ( 6   a,    6   b ); a releasable coupling means ( 26   a,    26   b,    27   a,    27   b,    28   a,    28   b ) between the stop member ( 23   a,    23   b ) and the second element ( 13   a,    13   b ), the nut also being provided with an area for direct clamping between a first clamping surface ( 20   a,    20   b ) of the first element ( 6   a,    6   b ) and a second clamping surface ( 21   a,    21   b ) of the second element ( 13   a,    13   b ), when the second clement ( 13   a,    13   b ) axially engages with the tip ( 3   a,    3   b ) or said adjacent part ( 5 ) to be assembled.

FIELD OF THE INVENTION

The present invention relates to a self-locking screwing attachmentdevice including a nut screwed onto a threaded tip.

The present invention also relates to an assembly of at least two partsattached to each other by such a device.

The self-locking attachment device has the object to prevent two partsfrom being importunately unscrewed with respect to each other, inparticular in applications where both pieces are subjected when operatedto vibrations or shakes. This is applicable to an assembly of three ormore parts.

1. State of the Art

Self-locking screwing attachment devices for securing at least two partsto each other, having generally the form of a nut screwed onto athreaded tip, provided with strengthened releasable coupling means, forpreventing said at least two parts from being importunately unscrewed,are known. This strengthened coupling means perform a self-locking ofthe coupling when screwing the nut on the tip.

These known devices generally have drawbacks of several kinds:

the nut consists of several separable parts which can be lost and shouldbe assembled according to an accurate order,

nut not adapted to parts to be assemble and/or to threaded tips havingmultiple shapes and not necessarily standard; the friction surfacesrequired for the clamping are highly dependent on the shape of parts tobe assembled, resulting in an uncertain clamping efficiency according toconfigurations; the adaption of these known nuts sometimes requires asignificant and extensive machining,

poorly optimized dimensions.

2. Purpose of the Invention

The purpose of the invention is to overcome all or part of the previousdrawbacks by providing a self-locking screwing attachment device forattaching at least two parts to each other, which is compact, made as asingle piece, adaptable to configurations and shapes of multiplenon-standard parts, or demanding as little machining as possible.

OBJECT(S) OF THE INVENTION

For that purpose, one object of the invention is to provide aself-locking screwing attachment device including a nut screwed onto athreaded tip extending along a screwing axis, characterised in that thenut includes:

a first element rotating relative to the tip during screwing;

a second element rotatably engaged with the tip or an adjacent part tobe assembled, the tip passing therethrough;

a stop member rotatably secured to the first element;

a releasable coupling means between the stop member and the secondelement,

the nut also being provided with an area for direct clamping of a firstclamping surface of the first element and a second clamping surface ofthe second element against each other, when the second element axiallyengages the tip or said adjacent part to be assembled.

Thus, the tightening force is perfectly controlled since it isconditioned by respective clamping surfaces of two constituent elementsof the nut. Furthermore, only a rotating stop between the second elementand an adjacent part or the threaded tip is to be provided, whichgenerates a minimal machining of said adjacent part or tip, whileensuring a quite reliable locking, in view of the releasable couplingmeans provided.

According to other advantageous characteristics of the invention, thesecond element is movable in the axial direction X with respect to thefirst element, between an axial stop carried by the first element andthe stop member, the latter being urged towards the second element byreturn means resting on the first element, and being driven intranslation along the axis against the return means with respect to thefirst element, under the influence of the second element, as the nut ismoved along the axis during screwing, when the second element axiallyengages the tip or said adjacent part to be assembled.

Due to the axial stop retaining the second element onto the firstelement, the nut has the form of a single unit, exempting differentcomponents from being gathered and assembled, which makes it particularsimple to use.

According to yet other advantageous characteristics of the invention,the coupling means include axially directed teeth formed on the secondelement and on the stop member, interpenetrable when biased by thereturn means.

According to yet other advantageous characteristics of the invention,the first element includes an area for being rotatably engaged with ascrewing tool, said area axially bounded by a back end of the nut withrespect to the axial screwing direction, and by a shoulder formed on theperiphery of the nut.

According to yet other advantageous characteristics of the invention,the nut includes a supporting cylinder fastened at its back end to afront face of the shoulder, a face of the front end of the cylindermaking up the first clamping surface of the first element.

According to yet other advantageous characteristics of the invention,the stop member has generally an annular shape introduced into a throathaving a substantially cylindrical shape, bounded on the one handinternally by a cylindrical portion substantially extending the area forrotatable engagement beyond the peripheral shoulder, in the screwingdirection of the nut, and on the other hand externally by the supportingcylinder, the stop member further including rotating stop meansconsisting of at least one radial protrusion, for example havinggenerally a dovetail shape axially sliding in a groove having aconjugated shape provided in the thickness of the supporting cylinder, afront face of the stop member with respect to the screwing directionsupporting part of the teeth of the coupling means.

According to yet other advantageous characteristics of the invention,the second element has generally an annular shape a back face of whichwith respect to the screwing direction supports part of the teeth of thecoupling means, the second element having an inner shoulder the radiallyinner profile of which is sandwiched between the axial stop and the stopmember.

According to yet other advantageous characteristics of the invention,the second element includes at least one lug axially extending in thescrewing direction of the nut, the lug being capable of introductioninto a housing having a conjugated shape provided in the adjacent partto be assembled, so that the second element and said adjacent part arefast for common rotation together.

According to yet other advantageous characteristics of the invention,the return means are of the compression spring type, in particular ofthe wavy type.

According to yet other advantageous characteristics of the invention,the nut includes a supporting cylinder extending the area for rotatableengagement beyond the peripheral shoulder in the axial screwingdirection of the nut, wherein a front end of the supporting cylinderincludes a face making up the first clamping surface of the firstelement.

According to yet other advantageous characteristics of the invention,the stop member has generally an annular shape introduced into a throathaving a substantially cylindrical shape, bounded on the one handinternally by the supporting cylinder, and on the other hand externallyby a cover having generally a cylindrical shape secured to theperipheral shoulder and extending in the screwing direction up to afront end, the stop member further including rotating stop meansconsisting of at least one radial protrusion, for example havinggenerally a dovetail shape axially sliding in a groove having aconjugated shape provided in the thickness of the cover, a front face ofthe stop member with respect to the screwing direction supporting partof the teeth of the coupling means.

According to yet other advantageous characteristics of the invention,the second element has generally an annular shape a back face of whichwith respect to the screwing direction supports part of the teeth of thecoupling means, the second element having an outer shoulder the radiallyouter profile of which is sandwiched between the axial stop and the stopmember.

According to yet other advantageous characteristics of the invention,the second element includes at least one radially inner protrusionpenetrating a groove provided on the tip, so as to set a key type slidelink and thus rotatably secure the second element to the tip.

According to yet other advantageous characteristics of the invention,the return means are of the compression spring type, in particular acoiled spring.

According to yet other advantageous characteristics of the invention,the axial stop is formed by a shoulder, or a narrowed portion inparticular made by crimping, extending radially to inside the nut so asto trap the second element in the throat.

Still another object of the invention is to provide an assembly betweena support onto which is securely mounted a threaded tip and at least oneadjacent part (5) through which the tip passes, characterised in that itincludes a self-locking screwing attachment device having all or part ofthe preceding characteristics.

Still another object of the invention is to provide an assembly on athreaded tip of an adjacent part such as a pulley or a wheel, securelyrotatably mounted on the tip, in particular via a key system, theadjacent part being fitted onto the tip to the point of axially engaginga shoulder of the tip, characterised in that it includes a self-lockingscrewing attachment device having all or part of the precedingcharacteristics.

DETAILED DESCRIPTION

The invention will be better understood upon reading the descriptionthat follows of two non-limiting embodiments of the invention and inlight of the appended drawings wherein:

FIGS. 1 and 2 represent an assembly of two parts provided with ascrewing coupling device according to a first embodiment of theinvention, respectively in a preassembled configuration and in anassembled configuration,

FIG. 3 represents an enlarged view of FIG. 1 with a partialcross-section along a longitudinal cross-section plane,

FIG. 4 represents a perspective view of the nut of FIG. 1 with onequarter cut away in the longitudinal direction,

FIG. 5 represents an exploded view of the nut of FIG. 1.

FIG. 6 represents a view of the spring integrated to the nut of FIG. 1,

FIG. 7 represents an assembly of one part onto a threaded tip providedwith a coupling device according to a second embodiment of theinvention,

FIG. 8 represents a perspective view of the assembly of FIG. 7, with onequarter cut away in the longitudinal direction.

Generally in the following description, the screwing of the nut ismentioned along an axial direction X, which is coextensive to thelongitudinal axis of the threaded tip cooperating with the nut. Thewords “front” and “back” used throughout the text to structurallydescribe the invention should be understood in connection with thisaxial direction, and more precisely with the direction of movement ofthe nut when it is screwed onto the tip (screwing forwardly, unscrewingrearwardly).

There is represented in FIGS. 1 and 2 a self-locking screwing attachmentdevice la according to a first embodiment of the invention. This deviceincludes a nut 2 a screwed onto a threaded tip 3 a (or strut) so as toensure the attachment to each other of at least two parts, typically asupporting part 4 and an adjacent part 5, in the example represented. Inthis example, the threaded tip 3 a is rigidly mounted in a bore of thesupporting part 4. The adjacent part 5 has the tip 3 a passingtherethrough and is sandwiched between the supporting part 4 and the nut2 a. In an alternative not represented, the tip 3 a can be provided witha shoulder resting against a face of the supporting part 4 on theopposite side to the thread of the tip 3 a, so as to simultaneouslysandwich the supporting part 4 and the adjacent part 5 between theshoulder and the nut 2 a.

According to the invention, the nut 2 a includes a first element 6 arotating relative to the tip 3 a when screwing. In reference to FIGS. 1to 3, this first element includes several sections that can be brokendown from back to front into an area for rotatable engagement 7 a by ascrewing tool such as a wrench, a shoulder 8 a formed on the peripheryof the nut 2 a, and a cylindrical part 9 a, substantially extending thearea for rotatable engagement 7 a forwardly beyond the shoulder 8 a. Thearea 7 a has typically a prismatic external shape, for example asix-sided one. The first element includes an end-to-end through bore 10.A rear part 11 of the bore 10 is narrower and includes a thread 12cooperating with that of the tip 3 a when screwing.

The nut 2 a includes a second element 13 a having generally an annularshape located at a front end of the nut 2 a. The second element 13 aincludes an internal shoulder 14 a. The radially internal profile of theshoulder 14 a is fitted around a front end of the cylindrical part 9 aof the first element 6 a and is retained forwardly by an axial stop 15a, typically an elastic ring.

As soon as the lug 17 a is introduced into the housing 18, the secondelement 13 a is rotatably engaged with the adjacent part 5, that isrotatably unmovable with the same. It is assumed in this case that thepart 5 is itself rotatably unmovable with respect to the tip 3 a. Thesecond element 13 a includes a radial extension 16 a carrying a lug 17 aextending axially in the screwing direction of the nut 2 a, that isforwardly. The lug 17 a is for being introduced into a housing 18 havinga conjugated shape, for example a blind bore provided in the adjacentpart 5. In the example illustrated in FIGS. 1 and 2, there are providedtwo housings 18 arranged at 180° around the axis X, preventing thesecond element 13 a from being rotated one full rotation about the axisX before the lug 17 a is positioned opposite the housing 18.Alternatively, a single housing could be enough.

As can be seen in FIG. 3, the nut 2 a also includes a supportingcylinder 19 a fastened at its back end to a front face of the shoulder 8a. A face of the front end of the cylinder 19 a makes up a firstclamping surface 20 a for axially engaging a second clamping surface 21a located in front of the same on a back face of the second element 13a. The supporting cylinder 19 a forms a spacer restricting theadvancement of the first element 6 a with respect to the second element13 a when the nut 2 a is being screwed onto the tip 3 a. The cylinder 19a is for example welded to the shoulder 8 a. A substantially annular orcylindrical throat 22 a is provided between the cylindrical part 9 a andthe supporting cylinder 19 a which bound this throat internally andexternally, respectively.

The nut 2 a also includes a stop member 23 a having generally an annularshape introduced into the throat 20 a. The stop member 23 a is rotatablysecured to the first element 6 a. For that purpose, the stop member 23 aincludes at least one radial protrusion 24 a, typically two protrusions24 a as represented in FIGS. 1 to 5. These protrusions 24 a areintroduced and axially slide in grooves 25 having conjugated shapesprovided in the thickness of the supporting cylinder 19 a (FIGS. 5).These protrusions have for example dovetail shapes, the flared zone ofwhich is the farthest from the axis X, these protrusions beingintroduced into respective grooves having also a trapezoidalcross-section. Such a trapezoidal shape ensures an optimum guidance ofthe stop member when axially moved into the throat 22 a.

According to the invention, the nut 2 a also includes releasablecoupling means 26 a, 27 a, 28 a consisting of two groups of axiallydirected teeth, fastened for a first group to the stop member 23 a, andfor the second group to the second element 13 a. One group of teeth 26 ais provided on a front annular face of the stop member 23 a and anothergroup of teeth 27 a is provided on a back annular face of the secondelement 13 a facing said front face. The teeth have a triangularconfiguration and have more precisely an isosceles shape, that is havefaces directed towards the other group of teeth and are of the sameoblique slope. The teeth 26 a of the stop member 23 a and the teeth 27Aof the second element 13 a have complementary profiles such that theyare interpenetrable when biased by the return means 28 a provided in thethroat 22 a, urging the stop member 23 a towards the second element 13a.

The first group of teeth 26 a of the stop member 23 a is rotatablydriven with the first element 6 a upon screwing the nut 2 a, whereas thesecond group of teeth 27 a of the second element 13 a is rotatablyunmovable. During this relative rotation between both groups of teeth,the latter are alternately in an interpenetration configuration and atip to tip configuration. The passage from one configuration to theother is performed by a relative sliding of the respective adjacentfaces of both groups of teeth. The stop member 23 a thereby performstranslations along the axis X alternately rearwardly and forwardly whenscrewing the nut 2 a, this being similar to an oscillation movement.Each translation is performed on a stroke corresponding to the height ofthe teeth, the distance separating the tip of one tooth from the troughbetween two teeth, projected on the axial direction.

The return means 28 a are typically formed by a wavy compression spring,as illustrated in FIG. 6, working on a relatively small axial stroke,induced by alternated translations of the stop member 23 a. The spring28 a rests on the one hand onto a shoulder of the first element 6 alocated at the bottom of the throat 22 a, and on the other hand on aback face of the stop member 23 a.

Screwing the nut 2 a onto the tip 3 a is performed the following way: asillustrated in FIG. 1, the nut is presented at the end of the threadedtip and then screwed thereto using an adapted wrench rotatably engagingthe nut. At the beginning of the screwing, the second element is freelyrotatable, and then moves closer to the adjacent part 5. When the nut 2a is being screwed, the second element 13 a rotates about the axis Xuntil the lug contacts the adjacent part 5. A further screwing of thenut further rotates the second element 13 a, until the lug 17 a clingsonto the first of the housings 18 located on its trajectory, in view ofthe axial forward thrust. This indexing of the lug onto the mouth of thehousing is automatically operated and generates a sensory effectperceived by the operator when screwing. The lug 17 a once in thisposition, will then penetrate the housing 18 as the screwing proceedsfurther and the nut advances towards the adjacent part 5. The secondelement 13 a is then rotatably unmovable with respect to the other partsof the nut 2 a. Any further rotation of the first element 6 a causes twoeffects: on the one hand, the first element 6 a will advance intranslation along the axis X towards the second element 13 a, as long asthere is nothing to stop this advancement. On the other hand, thecoupling means are biased by the relative sliding between both groups ofteeth 26 a, 26 b, which rotate with respect to each other at the sametime as an oscillation of the stop member 23 a is exerted against thethrust exerted by the return means 28 a. Thrusts and releases arealternately performed in the contact between both groups of teeth. Thisresults in a braking effect also called self-locking, preventing the nut2 a from being importunately unscrewed, since the same thrust andrelease phenomenon between the teeth is present when unlocking. Toovercome the thrust of the spring, a rotation torque should be appliedto the first element 6 a, which is higher than a given threshold, so asto generate either locking, or unlocking.

The screwing proceeds until the second element 13 a comes to pressagainst the adjacent part 5 and the supporting cylinder 19 a comes intocontact with the second element 13 a, by their respective clampingsurface 20 a, 21 a, as shown in FIG. 2. A clamping torque is finallyapplied to the first element 6 a, which is reflected by a suitableclamping directly exerted between the supporting cylinder 19 a and thesecond element 13 a.

A second embodiment of the invention is presented in FIGS. 7 and 8 onlywith respect to the differences from the first embodiment. Elementshaving references with the same base number (for example 2 a and 2 b)have identical technical functions or effects in both embodiments.

In this second embodiment, the assembly is made between a rotatingelement 30 such as a pulley, a wheel, etc. and a tip 3 b. The rotatingelement 30 includes a hub provided with a centre bore 31 enabling it tobe fitted onto the tip end, to the point of coming to rest onto ashoulder 32 of the tip 3 b. An anti-rotation device is provided betweenthe rotating element 30 and the tip 3 b, for example an internal radialprotrusion in the bore of the rotating element, forming a key,introduced into a longitudinal groove 33 formed on the end of the tip 3b.

A first element of the nut 2 b includes several sections which can bebroken down from back to front in an area for rotatable engagement 7 busing an adapted tool, a peripheral shoulder 8 b and a supportingcylinder 19 b.

The supporting cylinder 19 b extends the area for rotatable engagement 7b beyond the peripheral shoulder 8 b forwardly, that is in the screwingdirection of the nut 2 b.

The nut also includes a cover 9 b having generally a cylindrical shapefastened to the peripheral shoulder 8 b, and extending forwardly to afront end 34. A throat 22 b having a substantially cylindrical shape isbounded on the one hand internally by the supporting cylinder 19 b, andon the other hand externally by the cover 9 b.

The nut includes a stop member 23 b having generally an annular shape,introduced into the throat 22 b. The stop member 23 b includes rotatingstops means consisting of at least one radial protrusion 24 b axiallysliding in a groove having a conjugated shape provided in the thicknessof the cover 9 b. This protrusion can for example have generally adovetail shape having a flared part away from the axis X, ensuring anoptimum guidance of the stop member 23 b with respect to the cover 9 b.

In this embodiment, the second element 13 b has generally an annularshape having an external shoulder the radially external profile 14 b ofwhich is sandwiched between an axial stop 15 b and the stop member 23 b.The axial stop 15 b consists of a shoulder or narrowed portion, inparticular made by crimping, extending radially towards the axis X, soas to trap the second element 13 b into the throat 22 b.

As in the first embodiment, the second element 23 b includes rotatingstop means with respect to the first element 6 b, consisting of at leastone radially internal protrusion penetrating a longitudinal grooveprovided to the tip 3 b, so as to set a key type link. The groove canadvantageously be the groove 33 rotatably locking the rotating element30.

Coupling means 26 b, 27 b, 28 b consist of a first group of teeth 26 bprovided on a front annular face of the stop member 23 b, and a secondgroup of teeth 27 b provided on a back annular face of the secondelement 13 b.

A compression spring 28 b such as a coiled spring is provided in thethroat 22 b, and rests on a bottom of the throat 22 b to push the stopmember 23 b towards the second element 13 b, so as to generate theinterpenetration of the teeth. In an alternative not shown, a wavyspring is also suitable.

As in the first embodiment, direct clamping surfaces are providedbetween two constituent elements of the nut 2 b, that is a front annularface of the supporting cylinder 19 b, and a back annular face of thesecond element 13 b. The supporting cylinder 19 b forms a spacer as inthe first embodiment, by restricting the advancement of the firstelement 6 b to the second element 13 b, and allows a direct transmissionof the clamping force between the first element and the second elementbeing rotatably unmovable.

The operating principle of this second embodiment is similar to thefirst embodiment and will not be described in more details.

Schematically, the first and second embodiments are especially differentin that:

the supporting cylinder is located outside the coupling means in thefirst embodiment, whereas it is located inside the coupling means in thesecond embodiment,

the rotating stop of the second element is performed via the adjacentpart in the first embodiment whereas it is directly performed on thethreaded tip in the second embodiment,

the axial stop of the second element is performed by a cylindrical partand an elastic ring in the first embodiment whereas it is performed by anarrowed part of the cover in the second embodiment.

Of course, the invention is not restricted to the means just describedand includes all and any technical equivalents.

1. A self-locking screwing attachment device (1 a, 1 b) including a nut(2 a, 2 b) screwed onto a threaded tip (3 a, 3 b) extending along ascrewing axis (X), characterised in that the nut (2 a, 2 h) includes: afirst element (6 a, 6 b) rotating relative to the tip (3 a, 3 b) duringscrewing, a second element (13 a, 13 b) rotatably engaged with the tip(3 b) or an adjacent part (5) to be assembled, the tip (3 a) passingtherethrough, a stop member (23 a, 23 b) rotatably secured to the firstelement (6 a, 6 b), a releasable coupling means (26 a, 26 b, 27 a, 27 b,28 a, 28 b) between the stop member (23 a, 23 b) and the second element(13 a, 13 b), this coupling means consisting of two groups of axiallydirected teeth, secured for a first group to the stop member (23 a, 23b), and for the second group to the second element (13 a, 13 b), the nutbeing further provided with an area for direct clamping of a firstclamping surface (20 a, 20 b) of the first element (6 a, 6 b) and asecond clamping surface (21 a, 21 b) of the second element (13 a, 13 b)against each other, when the second element (13 a, 13 b) axially engagesthe tip (3 a, 3 b) or said adjacent part (5) to be assembled, the secondelement (13 a, 13 b) being movable in the axial direction (X) withrespect to the first element (6 a, 6 b), between an axial stop (15 a, 15b) carried by the first element and the stop member (23 a, 23 b).
 2. Thedevice according to claim 1, characterised in that the stop member (23a, 23 b) is urged towards the second element (13 a, 13 b) by returnmeans (28 a, 28 b) resting on the first element (6 a, 6 b), and beingdriven in translation along the axis (X) against the return means (28 a,28 b) with respect to the first element (6 a, 6 b), under the influenceof the second element (13 a, 13 b), as the nut (2 a, 2 b) is moved alongthe axis (X) during screwing, when the second element (13 a, 13 b)axially engages the tip (3 a, 3 b) or said adjacent part (5) to beassembled.
 3. The device according to claim 2, characterised in that theteeth (26 a, 26 b, 27 a, 27 b) of the second element (13 a, 13 b) andthe stop member (23 a, 23 b) are interpenetrable when biased by thereturn means (28 a, 28 b).
 4. The device according to claim 1,characterised in that the first element (6 a, 6 b) includes an area (7a, 7 b) for being rotatably engaged by a screwing tool, said areaaxially bounded by a back end of the nut (2 a, 2 b) with respect to theaxial screwing direction, and by a shoulder (8 a, 8 b) formed on theperiphery of the nut.
 5. The device according to claim 4, characterisedin that the nut (2 a, 2 b) includes a supporting cylinder (19 a, 19 b)secured at a back end thereof to a front face of the shoulder (8 a, 8b), a face of the front end of the cylinder (19 a, 19 b) making up thefirst clamping surface (20 a, 20 b) of the first element (6 a, 6 b). 6.The device according to claim 5, characterised in that the stop member(23 a) has generally an annular shape introduced into a throat (22 a)having a substantially cylindrical shape, bounded on the one handinternally by a cylindrical part (9 a) substantially extending the areafor rotatable engagement (7 a) beyond the peripheral shoulder (8 a), inthe screwing direction of the nut (1), and on the other hand externallyby the supporting cylinder (19 a), the stop member (23 a) furtherincluding rotating stops means (24 a) consisting of at least one radialprotrusion, for example having generally a dovetail shape axiallysliding in a groove having a conjugated shape provided in the thicknessof the supporting cylinder (19 a), a front face of the stop member (23a) with respect to the screwing direction supporting part of the teeth(26 a) of the coupling means.
 7. The device according to claim 3,characterised in that the second element (13 a) has generally an annularshape a back face of which with respect to the screwing directionsupports part of the teeth (27 a) of the coupling means, the secondelement (13 a) having an inner shoulder the radially inner profile (14a) of which is sandwiched between the axial stop (15 a) and the stopmember (23 a).
 8. The device according to claim 1, characterised in thatthe second element (13 a) includes at least one lug (17 a) axiallyextending in the screwing direction of the nut (1), the lug beingcapable of introduction into a housing (18) having a conjugated shapeprovided in the adjacent part (5) to be assembled, so as to rotatablysecure the second element (13 a) to said element part (5).
 9. The deviceaccording to claim 2, characterised in that the return means (28 a) areof the compression spring type, in particular of the wavy type.
 10. Thedevice according to claim 4, characterised in that the nut (1) includesa supporting cylinder (19 b) extending the area for rotatable engagement(7 b) beyond the peripheral shoulder (8 b) in the axial screwingdirection of the nut (1), wherein a front end of the supporting cylinderincludes a face making up the first clamping surface (20 b) of the firstelement (6 b).
 11. The device according to claim 10, characterised inthat the stop member (23 b) has generally an annular shape introducedinto a throat (22 b) having a substantially cylindrical shape, boundedon the one hand internally by the supporting cylinder (19 b), and on theother hand externally by a cover (9 b) having generally a cylindricalshape secured to the peripheral shoulder (8 b) and extending in thescrewing direction up to a front end, the stop member (23 b) furtherincluding rotating stop means (24 b) consisting of at least one radialprotrusion, for example having generally a dovetail shape axiallysliding in a groove having a conjugated shape provided in the thicknessof the cover (9 b), a front face of the stop member (23 b) with respectto the screwing direction supporting part of the teeth (23 b) of thecoupling means.
 12. The device according to claim 3, characterised inthat the second element (13 b) has generally an annular shape a backface of which with respect to the screwing direction supports part ofthe teeth (27 b) of the coupling means, the second element (13 b) havingan outer shoulder the radially outer profile (14 b) of which issandwiched between the axial stop (15 b) and the stop member (23 b). 13.The device according to claim 1, characterised in that the secondelement (13 b) includes at least one radially inner protrusion (17 b)penetrating a groove (33) provided on the tip (3 b), so as to set a keytype slide link and thus rotatably secure the second element (13 b) tothe tip (3 b).
 14. The device according to claim 2, characterised inthat the return means (28 b) are of the compression spring type, inparticular a coiled spring.
 15. The device according to claim 12,characterised in that the axial stop (15 b) is formed by a shoulder, ora narrowed portion in particular made by crimping, extending radially toinside the nut (2 b) so as to trap the second element (13 b) in thethroat (22 b).
 16. An assembly between a support (4) onto which issecurely mounted a threaded tip (3 b) and at least one adjacent part (5)through which the tip (3 b) passes, characterised in that it includes aself-locking screwing attachment device (1 a) according to claim
 1. 17.An assembly on a threaded tip (3 b) of an adjacent part (30) such as apulley or a wheel, securely rotatably mounted on the tip (3 b), inparticular via a key system, the adjacent part (30) being fitted ontothe tip (3 b) to the point of axially engaging a shoulder (32) of thetip, characterised in that it includes a self-locking screwingattachment device (1 b) according to claim 1.